Counter-top produce refrigeration and ozonation system and method

ABSTRACT

A produce storage chamber comprising a chamber capable of encasing produce, a refrigeration system, at least one ozone generation units, and at least one ethylene scrubbers. The chamber is capable of delaying postharvest produce deterioration using at least one of temperature control, ozone generation, and ethylene scrubbing.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a Continuation in Part claiming priority to U.S.patent application Ser. No. 13/013,327 filed on Jan. 25, 2011 entitled“Produce Refrigeration Chamber,” the contents of which are incorporatedby reference herein.

FIELD OF THE INVENTION

The present invention relates to the field produce storage chamber toreduce spoilage. More specifically, to a construction designed to fit ona counter top.

BACKGROUND OF INVENTION

Due to various nutrient and antioxidant profiles, consumption of freshproduce is generally accepted as essential to a healthy diet. Regularconsumption of fruit is associated with reduced risks of cancer,cardiovascular disease (especially coronary heart disease), stroke,Alzheimer's disease, cataracts, and some of the general functionaldeclines associated with aging. Diets that include a sufficient amountof fruits and vegetables also help reduce the chance of developingkidney stones and may help reduce the effects of bone loss. Fruits arealso low in calories and are often integral to weight loss plans andgenerally healthy, balanced diets.

Most fruits and vegetables ripen after they are removed from theirassociated plants and stalks. Such ripening often changes thecharacteristics of the produce, including altering sweetness levels,texture, and firmness. Consumption of fruits and vegetables at theoptimal point in the ripening process helps maximize not only taste andenjoyment of these foods, but may also maximize their health benefits.

Ripening is a natural process which is primarily a result of theproduction of ripening enzymes, many of which are triggered by therelease of ethylene by the produce. Ethylene is a simple hydrocarbon gasproduced when a fruit ripens, and is known to promote the upregulationof genes that cause the expression of enzymes that foster ripening.These enzymes may change the color of the skin as chlorophyll isdegraded, aid in the production of new pigments, foster the breakdown ofacids that make fruit taste sour, convert starches into sweet sugars,and soften pectin.

Maintaining most fruits and vegetables in a sufficiently cold stateafter harvest helps extend and ensure shelf life, most notably byreducing the release of ethylene. However, storage of produce in anisolated area without refrigeration causes a build up of ethylene andresults in faster ripening (and rotting) of fruits and vegetable.

Due to the costs and life spans of harvested fruits and vegetables,there have been many techniques developed to address storage to maintainthis cold chain. One such example is U.S. Pat. No. 4,845,958 entitled“Method of and Apparatus for Preserving Perishable Goods” to Senda. Theapparatus taught by Senda relates to a refrigerated housing thatincludes a humidifier and a compression system to cool the housing. Thedevice also uses an ethyl alcohol spray to help odorize the ripeningproduce.

A second concept for preserving ripening produce is introduced by U.S.Pat. No. 5,661,979 entitled “Self-contained Refrigeration Device forFruit” to Deboer. The Deboer patent teaches a self containedrefrigeration unit that uses thermo-electric Peltier cooler, as well asa heat sink to dissipate the heat generated by the cooler so to maintaina cooled container to maintain produce. A double-headed fan facilitatesairflow throughout the assembly to aid in the removal of ethylenethrough a vent tower.

Yet a third example of a system for preserving fruit and vegetables isfound in U.S. Pat. No. 5,782,094 entitled “Refrigerated Countertop SnackContainer” to Freeman. Akin to Daboer, Freeman uses a Peltierthermoelectric element (instead of a compressor) to cool a refrigerationcontainer. Such container is insulated and includes a series of airoutlet and intake vents to aide in circulating air about the produce inorder to reduce ethylene build up. The device further uses a series offins and baffles to aid in circulation.

Ozone is a pungent, naturally-occurring gas possessing strong oxidizingproperties, and has a long history of safe use in the disinfection ofwater sources. Ozone rapidly attacks bacterial cell walls and isgenerally thought to be a more effective anti-pathogenic agent againstplant spores and mammalian parasites than chlorine. Ozone is reported tohave 1.5 times the oxidizing potential of chlorine, yet contact timesfor this antimicrobial action are typically 4-5 times less than that ofchlorine, all without the unwanted byproducts associated with chlorine.Ozone is also known to degrade ethylene.

As shown by the foregoing references, there are certain limitations incurrent counter-top style devices used to maintain fruits andvegetables. First, these devices are limited to using the Peltier effect(or traditional vapor compression systems) in combination with airflowto ward off the effects of ethylene build up. Second, current designsare largely inefficient and consume large levels of energy. Third, mostof these designs fail to provide effective treatment of the ethylenewhich is the root of rotting and spoilage of the produce. Fourth, thereare no counter-top applications of produce storage that introduce ozoneas a means of preventing produce spoilage. Accordingly, there is a needin the art of produce storage for an energy efficient and robust chamberfor use with fresh fruits and vegetables.

SUMMARY OF THE INVENTION

In view of the foregoing background, it is therefore an object of thepresent invention to provide a table top, stackable, produce chambercomprising a chamber capable of encasing produce, having a refrigerationsystem, at least one ozone generation unit, and at least one ethylenescrubbers. The chamber is therefore capable of delaying postharvestproduce deterioration using of temperature control, ozone generation,and ethylene scrubbing.

In one embodiment, the present invention contemplates a portable producechamber comprising a housing having a size and dimension to fit on akitchen countertop, the housing comprising a chamber capable of encasingproduce. In one embodiment, the chamber is shaped so that one chamberwill securely stack on another chamber of the same type. At least oneethylene scrubber is fitted within the chamber capable of reducingchamber ethylene gas concentrations to delay postharvest producedeterioration. The chamber is in communication with a refrigerationsystem for the purpose of maintaining a chamber temperature that delayspostharvest produce deterioration. Additionally, the refrigerationsystem maintains a chamber relative humidity that delays postharvestproduce deterioration. Lastly, an ozone generator in communication withthe chamber maintains a chamber ozone concentration for the purpose ofdelaying postharvest produce deterioration.

The invention also contemplates a method of reducing postharvest producedeterioration comprising the steps of: placing produce in a chamber;encasing the produce within the chamber; cooling the chamber to atemperature from about 10° C. to 20° C.; introducing gaseous ozone intothe chamber to maintain a chamber ozone concentration between about 0.05ppm and 0.1 ppm; and maintaining a relative humidity within the chamberranging from about 70% to 100% relative humidity.

BRIEF DESCRIPTION OF THE DRAWINGS

For a fuller understanding of the invention, reference is made to thefollowing detailed description, taken in connection with theaccompanying drawings illustrating various embodiments of the presentinvention, in which:

FIG. 1 is a perspective view of the produce chamber;

FIG. 2 is a right side view of the produce chamber;

FIG. 3 is a left side view of the produce chamber;

FIG. 4 is front view of the produce chamber;

FIG. 5 is an exploded view of the components of the produce chamber;

FIG. 6 is a perspective view of the refrigeration system within theproduce chamber; and

FIG. 7 illustrates the preferred thermoelectric plate (TE) used withinthe produce chamber.

FIG. 8 is a diagram of one embodiment of an ozone generator circuit.

DETAILED DESCRIPTION OF THE INVENTION

In the Summary of the Invention above and in the Detailed Description ofthe Invention and in the accompanying drawings, reference is made toparticular features (including method steps) of the invention. It is tobe understood that the disclosure of the invention in this specificationincludes all possible combinations of such particular features. Forexample, where a particular feature is disclosed in the context of aparticular aspect or embodiment of the invention, that feature can alsobe used, to the extent possible, in combination with and/or in thecontext of other particular aspects and embodiments of the invention,and in the invention generally.

The term “comprises” is used herein to mean that other elements, steps,etc. are optionally present. When reference is made herein to a methodcomprising two or more defined steps, the steps can be carried in anyorder or simultaneously (except where the context excludes thatpossibility), and the method can include at least one steps which arecarried out before any of the defined steps, between two of the definedsteps, or after all of the defined steps (except where the contextexcludes that possibility).

In this section, the present invention will be described more fully withreference to the accompanying drawings, in which preferred embodimentsof the invention are shown. This invention may, however, be embodied inmany different forms and should not be construed as limited to theembodiments set forth herein. Rather, these embodiments are provided sothat this disclosure will be thorough and complete, and will convey thescope of the invention to those skilled in the art.

As illustrated in FIGS. 1 through 6, the invention is directed to aproduce chamber 100 used to store fruits, vegetables other relatedperishable foods to ensure ripeness. The produce chamber 100 helpsregulate the temperature and humidity of fruits and vegetables and toensure regulated and reduced levels of ethylene. In doing so, theproduce chamber 100 helps maintain the proper ripeness of produce storedwithin its confines. While the invention contemplates a design for useon a kitchen countertop, the underlying technology can be used inrelated units, including produce chambers 100 that are stackable (i.e.,for use as displays at grocers to maintain fruits and vegetables), andproduce chamber 100 that are equal in size to current grocery storerefrigeration units.

As shown in FIG. 1-5, the components 101 of the produce chamber 100comprises an outer housing 200, a door 300 maintained by the outerhousing 200, a refrigeration system 400 and a controller 500 to helpregulate temperature, humidity, ozone, and ethylene concentration. Inaddition, the invention contemplates placement of a series of perforatedtrays 600 and a produce hook 630 within the outer housing 200 which helphold and maintain the stored produce. Other additional and relatedcomponents will be known and understood by those of ordinary skill inthe art upon review of the figures and this disclosure.

The Outer Housing

FIGS. 1 through 5 illustrate, by way of example, one embodimentcontemplated by the invention for the outer housing 200. First turningto FIG. 1, the outer housing 200 may include a first side panel 210, asecond side panel 220 and a base plate 230 (shown in greater detail inFIG. 5). The side panels 210 and 220 are essentially parallel to oneanother in order to form two respective ends of the produce chamber 100.The base plate 230 is inter-dispersed between both side panels 210 and220. Combination of these panels 210 and 220, as well as the base plate230 function as the outer casing of the outer housing 200. This providesa rigid shell for the outer housing 200 in order to protect theintegrity of the stored fruits and vegetables. What is more, such rigidshell further serves as a platform in which the various interiorcomponents 101 (shown in FIG. 5) are maintained and held within theproduce chamber 100.

FIG. 2 further illustrates one preferred shape, structure, andconfiguration for the first side panel 210. The first side panel 210 notonly functions as part of the rigid outer housing 200, but alsomaintains two primary components of the produce chamber 100. As shown inFIG. 2 (as well as FIG. 5), the first side panel 210 has a sufficientshape to house both the refrigeration system 400 and the controller 500.The first panel 210 further allows for the separation of the cold andhot sides of the refrigeration system 400 as well as to cool the variouscomponents housed by the first panel 210. Moreover, this allowscirculation of cooled, ozonated, and humidity controlled air inside theproduce chamber 100 for purposes of removing ethylene and inhibitingmicrobe proliferation.

As shown in both FIG. 1 and FIG. 2, the first panel 210 is preferably acircular disk 211 having an essentially flat bottom portion 212. Thebottom portion 212 illustrated in FIG. 2 mirrors the width of the baseplate 230 (shown in FIG. 4). As also shown in FIG. 5, the base plate 230perpendicularly engages the first flat wall 213 of the first side panel210. This allows the bottom portion 212, and accordingly the entireproduce chamber 100, to rest on a flat surface like a kitchencountertop—or alternatively a display counter (such as in a grocerystore). Of course, other shapes, such as a substantially rectangularproduce chamber 100 are also contemplated by this disclosure.

Turning back to FIG. 1 (and also to FIG. 4), the structure of the firstpanel 210 also includes an isolation plate 214 (in addition to the firstflat wall 213 and the bottom portion 212). The isolation plate 214 isessentially circular, conforming to the shape of the bottom portion 212.Moreover, the isolation plate 214 has a sufficient wall thickness so asto house and maintain the various components 101—which may include boththe refrigeration system 400 and the controller 500 in a separatecompartment from the main produce-storing chamber of the produce chamber100.

As shown in both FIG. 1 and FIG. 2, both the first flat wall 213 and theisolation plate 214 may include a series of vents 216. As shown, thesevents 216 preferably include a side vent 217, a panel vent 218 and a fanvent 219. As shown in greater detail in FIG. 5, the primary function ofthe side vent 217 and the panel vent 218 is to allow the hot side heatsink fan 482 (shown in FIG. 7) to pull ambient air in through the sidevent 217 and the panel vent 218, move it across the hot side heat sink481 and then push the now hot air out through fan vent 219 so as toremove heat from the refrigeration system 400. The secondary purpose isto pull ambient air in through the side vent 217 and panel vent 218 tocool the controller 500.

Both FIG. 3 and FIG. 5 illustrate, by way of example, the structure,positioning and features of the second panel 220. As shown, the secondpanel 220 mirrors the size and dimension of the first panel 210.Furthermore, the second panel 220 comprises a circular disk 221 having asecond flat wall 223, a second flat bottom portion 222, and a secondring 224 of similar construction compared to the first panel 210. Suchbottom portion 222 mirrors the width of the base plate 230 (again shownin FIG. 1 and FIG. 5).

FIG. 5 illustrates, by way of example, the structure and features of thebase plate 230. As shown, the base plate 230 preferably includes a frontraised edge 231, a bottom panel 232, a back raised edge 233 and adivider groove 234. The front raised edge helps engage and creating asealing relationship with the door 300. Similarly, the back raised edge233 both meets and connects to the back panel 350. The divider groove235 is a slit that has a sufficient length and depth so as to engage andmaintain at least one perforated trays 600.

The Door and Back Panel

Both FIG. 4 and FIG. 5 illustrate, by way of example, the structure andcharacteristics of both the door 300 (which optionally may betranslucent) and the back panel 350 which, along with the outer housing200, form the exterior of the produce chamber 100. First turning to FIG.4, the door 300 includes a first edge 301, a corresponding second edge302, a top edge 303 and a corresponding bottom edge 304. Moreover, atleast a portion of the door 300 is preferably transparent andaccordingly “see through”—such that a user may be able to view thecondition and quantity of fruits and vegetables within the producechamber 100. Preferably, a handle 340 is positioned proximate the bottomedge 304 of the door 300. The handle 340 helps make it easier to lift upand open the door 300 to retrieve (or alternatively store) produce.

As shown in FIG. 5, the first edge 301 of the door 300 is preferablyarced. This curvature should be substantially the same as that of theisolation plate 214 of the first panel 210. Likewise, the second edge302 should have curve that mirrors that of the second ring 224 of thesecond panel 220. Accordingly, when the door 300 is shut, a seal 310forms between the first edge 301 and the isolation plate 214 (andcorrespondingly, the second edge 302 and the second ring 224). Inaddition, the bottom edge 304 forms a bottom seal 320 with the frontraised edge 231 of the base plate 230.

FIG. 1-5 further illustrates, by way of example, the salient components101 of the back panel 350. As shown, the back panel 350 includes a firstedge 351, a corresponding second edge 352, a top edge 353, and a bottomedge 354. The first edge 351 is sufficiently curved to match the shapeof the first panel 210, while the second edge 352 is likewise arced tomirror the diameter of the second panel 220. As further shown, thebottom edge 354 forms a bottom seal 360 with the back raised edge 233 ofthe bottom plate 230.

A top hinge 390 connects the top edge 301 of the door 300 with the topedge 351 of the back panel 350. As shown, the top hinge 390 allows thedoor 300 to swivel open and allow access the various fruits andvegetables within the produce chamber 100. Optionally, the back panel350 may include an insulating layer 380. This insulating layer can besandwiched between the back panel 350 and an interior panel 385. Suchinsulating layer 380 increases the efficiency of the system and reducesthe need for the refrigeration system 400 to constantly run to providecooled air within the produce chamber 100.

Perforated Trays

FIG. 5 further illustrates, by way of example, the positioning andorientation of the perforated trays 600 within the produce chamber 100.As shown, the perforated trays 600 preferably include a horizontal tray610 and a corresponding vertical tray 620. Both trays 610 and 620include a plurality of holes 601 to allow air to circulate. This helpsensure the reduction of ethylene within the produce chamber 100, as wellas regulated internal temperature monitored by the controller 500.

As further shown in FIG. 5, the horizontal tray 610 is maintainedthrough a slit 611 found within the second panel 220. In contrast, thevertical tray 620 is maintained by both the horizontal tray 610 as wellas the divider groove 234 located on the base plate 230. Optionally, ahook 630 can be affixed to the top hinge 390 sufficient to hold andmaintain bananas and similar fruits within the produce chamber 100.

The Refrigeration System

Both FIG. 5 and FIG. 6 illustrate, by way of example, one embodiment ofthe refrigeration system 400. While several refrigeration systems 400are capable of being used within the produce chamber 100, the inventioncontemplates utilization of a cooling means, comprising at least one ofan ammonium absorption (AAF) system 410, a Peltier effect thermoelectric(TE) cooling system 450, or a vapor-compression refrigeration (VCR)system (not shown). While FIG. 5 illustrates this two-part refrigerationsystem 400, the invention also teaches use of just a single AAF system410 without need for the TE system 450 or use of a single TE system 450without the need for an AAF system 410, or the use or a single VCRsystem, or the use of a VCR system combined with a TE 450 or an AAF 410system.

Both FIG. 5 and FIG. 7 illustrate a TE system 450 generally comprised ofa thermoelectric (TE) module 460 which is comprised of a cold side plate470 and a hot side plate 480 and corresponding cold side heat sink 471and cold side heat sink fan 472 and hot side heat sink 481 and hot sideheat sink fan 482. When electricity is applied to the TE module 460 thecold side plate 470 cools down and the hot side plate 480 heats up. Acold side heat sink 471 is thermally coupled to the cold side plate 470which allows heat to be efficiently transferred from the inside of theproduce chamber 100 to the cold side plate 470. A cold side heat sinkfan 472 increases the efficiency of the entire system. The cold sideheat sink fan 472 also works to keep the air within the produce chamber100 moving through the zeolite filter 491.

As further illustrated by FIG. 7, heat absorbed by the cold side plate470 is transferred to the hot side plate 480. This heat is transferredthrough the thermally coupled hot side heat sink 481 which locatedoutside of the produce chamber 100. The hot side heat sink fan 482 isused to efficiently remove the heat from the hot side heat sink 481.This heat is vented out through the fan vent 219.

FIG. 5 illustrates an AAF system 410 comprised of a boiler 420, ammonia421, a condenser 422, an evaporator 423, a storage tank 424, and anabsorber 425. A concentrated ammonia solution 421 is heated in theboiler 420 and driven off as vapor. The pressurized ammonia 421 gas isthen liquefied in a condenser 422. Supplied with hydrogen, it evaporatesin the evaporator 423 and extracts heat from the storage container 424.The ammonia 421 gas then enters the absorber 425 where it is reabsorbedin a weak solution of ammonia 421. Finally, the saturated solution flowsback to the boiler 420 where the whole cycle starts again.

FIG. 6 illustrates one arrangement for the various components 101 of thetwo-part refrigeration system. Since the TE system 450 cools the producechamber 100 by extracting heat from it. This heat must ultimately beremoved from the entire produce chamber 100. In turn, the AAF system 410starts by heating ammonia 421 in the boiler 420. The boiler 420 can beheated by any number of means; all that matters is that heat is providedto the boiler 420. The invention specifically contemplates combinationof both a TE system 450 and an AAF system 410, wherein the heat from theTE system 450 hot side heat sink 481, (which is normally wasted energythat must be removed from the produce chamber 100), be used to heat theAAF system 410 boiler 420. By using what would normally be wasted heatfrom the TE system 450 to drive the AAF system 410, the overallefficiency of the produce chamber 100 is dramatically increased.

The Controller and Scrubber

The controller 500 is best illustrated in FIG. 5. There are threeprimary functions of the controller 500 contemplated by the invention.First, the controller 500 constantly monitors the temperature andhumidity within the produce chamber 100. Such information may bedisplayed by a digital readout 510 positioned and located on the firstpanel 210. Second, the controller 500 operates the refrigeration system400. Such operation may include determining when to turn on the AAFsystem 410 and/or the TE system 450.

As a third duty, the controller 500 can also opt to circulate alreadycooled air within the produce chamber through a scrubber 490—forpurposes of removing toxins such as ethylene which may lead to prematureripening of the fruits and vegetables contained within the producechamber 100.

Ethylene Scrubbing

To foster ethylene removal from the produce chamber 100, media for thepurpose of scrubbing ethylene from the air is present in the producechamber 100. The media is at least one of activated alumina,vermiculite, zeolite, and silica gel. The media is impregnated withpotassium permanganate (KMnO₄). The mass of media utilized is tailoredto the size of the produce chamber 100. Media pore size, pore volume,surface area, and bulk density is also tailored to the size of theproduce chamber 100. Media with lower bulk density is desired over thesame mass of media possessing a higher bulk density, due to the greatersurface area of the lower bulk density media providing greateravailability of KMnO₄ to ethylene gas. The mass, pore size, pore volume,surface area, and bulk density required for the produce chamber 100 willbe readily apparent to those skilled in the art. The media performs twoprimary functions: 1) to provide an absorptive surface to trap ethylenegas molecules, and 2) to provide a substrate on which KMnO₄ is carried.KMnO₄ is an oxidizing agent that reacts with ethylene, oxidizing it toethylene glycol which does not markedly affect produce ripening. Theproduce chamber 100, in a preferred embodiment, comprises at least onesachet containing 5 mg KMnO₄ impregnated zeolite. Besides or inconjunction with sachets, KMnO₄ impregnated filters and pellets may beused in the chamber 100. In another embodiment, ultraviolet lightmediated photcatalysis of titanium oxide reduces ethylene levels in theproduce chamber 100 (the ultraviolet light source is opticallysequestered from the produce). In one embodiment of the produce chamber100, at least one dedicated pocket, bag, shelf, hook, or net provides alocation for at least one sachet containing ethylene scrubbing media.

Titanium dioxide is known to be a photocatalyst under ultraviolet (UV)light. When Titanium dioxide is spiked with nitrogen ions or doped withmetal oxide like tungsten trioxide, it is also a photocatalyst undereither visible or UV light. The titanium dioxide photocatalytic reactionbreaks down ethylene gas into carbon dioxide and water vapor.Additionally, photocatalytic oxidation provides the added benefit ofreducing bacteria, molds, and odors. In one embodiment of the invention,a titanium dioxide photocatalyst is in communication with the producechamber 100 for the purpose of scrubbing ethylene gas and preventing thepremature ripening and spoiling of the fruits and vegetables containedwithin the produce chamber 100.

Ozone Generation

Ozone cannot be stored and transported like most other industrial gases,so must therefore be locally produced. Ozone can be produced in a numberof ways known in the art. The most common methods are by the use ofultraviolet light and coronal discharge.

In one embodiment of the invention ozone is generated with anultraviolet (UV) lamp. A UV lamp emitting light at approximately 185 nmin the presences of air (which is approximately 21% oxygen) will causesome diatomic oxygen (O₂) molecules to split, resulting in single oxygenatoms (O⁻) that bind to other diatomic oxygen molecules to form ozone(O₃). UV mediated ozone generation is advantageous in the currentinvention, for it is not susceptible to nitric oxide formation, as aresome corona discharge-based devices operating in a humid environment.

The coronal discharge method of ozone is employed for many industrialand personal uses. While multiple variations of the “hot spark” coronaldischarge method of ozone production exist, these units usually work bymeans of a coronal discharge tube. Coronal discharge tubes are typicallycost-effective and do not require an oxygen source other than theambient air to produce ozone. In one embodiment of the invention, ozoneis generated with a corona discharge device. In such a device, airpasses through an electrical field wherein ozone is generated. Thepreferred embodiment of an ozone generator is a variation of the coronaldischarge method.

FIG. 8 illustrates one embodiment of a circuit 80 used to drive thegeneration of ozone via coronal discharge. This circuit 80 comprises asilicon controlled rectifier Q1, which is a PNPN four-layersemiconductor device that normally acts as an open circuit, but switchesrapidly to a conducting state when an appropriate gate signal is appliedto the gate terminal. In this application, it operates as a full waverectified high voltage on-off generator to drive the primary winding ofstep up transformer T001. As the forward voltage across the anode andcathode is adjusted by the potentiometer R5, the amount of current intothe transformer and the rate of oscillation is controlled.

A suppression (“snubber”) circuit comprising a resister R4 and capacitorC2 protect the silicon controlled rectifier Q1 from overvoltage damage.Gate turn-on current is supplied by resister R2. Diodes D2 and D3complete the full wave circuit. Capacitor C1 provides alternatingcurrent isolation as well as adequate current to drive the circuit 80.

A glass electrode 82 in communication with the circuit 80 of isultimately responsible for the production of ozone. As the primarywinding of the transformer T001 is excited, the secondary winding of thetransformer T001 drives a high voltage potential into a coiled metalelement inside the electrode 82 that exceeds the dielectric breakdown ofdry air, which in turn excites electrons to produce a positive coronathat is initiated by an exogenous ionization event in a region of highpotential gradient. The electrons resulting from the ionization areattracted toward the coiled electrode, and the positive ions repelledfrom it. By undergoing inelastic collisions closer and closer to thecurved electrode, additional molecules are ionized in an electroncascade. The electron collisions excite the positive ions so thatphotons of short wavelength light are emitted. It is this that gives ablue-purple corona discharge its characteristic glow. These photons playan important part in producing the new seed electrons which are requiredto sustain the corona and for ozone to be continuously produced. Thelevels of ozone produced by this circuit and electrode combination, wheninstalled in the produce chamber are between 0.05 ppm and 0.1 ppm ozone,and preferable at around 0.09 ppm. Because of the high reactivity ofozone, materials employed in electrode construction include stainlesssteel (quality 316L), titanium, aluminum (as long as no moisture ispresent), glass, polytetrafluorethylene, or polyvinylidene fluoride.Silicone rubbers may also be employed since ozone concentrations in thepresent invention are relatively low.

Method of Reducing Postharvest Produce Deterioration

The present invention contemplates a method of reducing the severity ofpostharvest produce deterioration. The method preferably utilizes theproduce chamber 100 described herein. The method includes the step ofplacing of produce in a chamber of a suitable size and dimension toencase the produce. The produce chamber 100 is capable of beingsubstantially sealed. The chamber is cooled to a temperature rangingfrom 10° C. to 20° C., with the preferred temperature being 13° C.Additionally, ozone is introduced into the chamber so that a chamberozone concentration is maintained from 0.05 ppm to 0.1 ppm, with apreferred concentration range between 0.075 ppm and 0.95 ppm. In apreferred embodiment, a high cutoff point of approximately 0.09 ppmozone is maintained to ensure that ozone levels remain below permissiblelevels as established by Occupational Health and Safety Administration(OSHA) regulations. In a preferred embodiment, the ozone is introducedinto the chamber 100 by an ozone generator that is installed within thechamber. In one embodiment, ethylene is scrubbed from the chamberenvironment. In a preferred embodiment, ethylene concentrations withinthe chamber remain below 0.015 ppm. Preferably, 5-gram sachets ofpotassium permanganate are placed within the chamber 100 for the purposeof ethylene scrubbing, though other methods of ethylene scrubbing willbe clear to those skilled in the art. The step of maintaining a relativehumidity from 70% to 100% within the chamber is also contemplated with apreferred relative humidity level being about 95%. The chamber 100 isplaced on a counter top surface, such that as found in a residential orcommercial kitchen environment. In an alternative embodiment, onechamber 100 is stacked on another chamber 100 so that multiple chambersform a stacked chamber array.

Examples and Experimental Data

The following experimental data compared the post-harvest degradation ofbananas and tomatoes in various conditions. The control (“roomcondition”) temperatures ranged from approximately 22° C. to 25° C.,while experimental refrigerated temperatures ranged from approximately12° C. to 15° C. Relative humidity for control groups was maintained atapproximately 25% RH to 50% RH, while experimental groups weremaintained between approximately 85% RH to 100% RH. Ethylene gasconcentrations were maintained in control groups between approximately0.02 ppm and 0.035 ppm, while some experimental groups were maintainedbetween approximately 0.0 ppm and 0.01 ppm. Ozone was not introduced incontrol groups, while some experimental groups were maintained betweenapproximately 0.08 ppm and 0.095 ppm ozone, which is within theacceptable level range allowed by the Occupational Safety and HealthAdministration (OSHA) regulations for such an application.

TABLE 1 Moisture Loss per Banana/Tomato (after 21 Days) BANANA TOMATO %Moisture % Moisture STORAGE CONDITION Mass Loss Mass Loss OZONE TREATED18.1 g 10.5% 3.4 g 2.6% (13° C.) OZONE + ETHYLENE 12.1 g 5.3% 2.1 g 1.6%SCRUBBING (13° C.) AMBIENT/ROOM 86.2 g 38.4% 7.2 g 5.5% TEMPERATURE*Note: The standard error of the mean between treatments for bananas is27.8 g and for tomatoes is 1.5 g

Bananas and tomatoes were generally weighed every 2 days to trackmoisture loss. Table 1 summarizes the amount of moisture lost perindividual banana or tomato for each storage condition. There was only aminimal discrepancy between the amount of moisture lost in the two 13°C. storage treatments. Moisture loss was lower in the treatment withadditional ethylene scrubbing for both bananas and tomatoes, but thedifference was within the standard error and thus was not statisticallysignificant. However, fruit left exposed to the ambient/room temperatureconditions were found to lose much more moisture. From these results, itcan be concluded that lower temperatures with higher RH result inimproved water retention in these fruit. Furthermore, it is possiblethat the removal of additional ethylene using ethylene scrubbing sachetsmay improve the water retention.

TABLE 2 Banana Firmness Evaluated at 6 mm Deformation (Force in kg)OZONE & ETHYLNE OZONE SCRUBBING CONT (ROOM (13° C.) (13° C.)TEMPERATURE) DAY 0 4.226 4.159 4.191 DAY 6 3.522 3.772 1.973 DAY 123.031 3.438 1.052 DAY 14 2.869 3.381 0.601 DAY 16 2.972 3.656 0.391 DAY19 2.557 3.013 0.356 DAY 21 2.534 3.128 0.402

Table 2 shows that bananas in both of the 13° C. storage treatmentsexhibited improved preservation of firmness over bananas in ambient/roomconditions. This is indicated by higher force values for the bananasstored at 13° C., particularly with the bananas in the ozone withethylene scrubbing treatment. Thus, the treatment with ozone andethylene scrubbing provided better preservation of firmness over thetreatment with ozone only.

TABLE 3 Tomato Firmness Evaluated at 3 mm Deformation (Force in kg)OZONE OZONE & ETHYLNE CONT (ROOM (13° C.) SCRUBBING (13° C.)TEMPERATURE) DAY 0 3.004 2.988 2.959 DAY 06 2.354 2.418 1.533 DAY 122.168 2.291 1.192 DAY 14 2.187 2.197 1.207 DAY 16 2.142 1.967 1.367 DAY19 1.825 1.541 1.197 DAY 21 1.619 1.468 1.082

Table 3 shows that tomatoes in the 13° C. storage treatments generallyexhibited improved preservation of firmness compared with tomatoes inthe ambient/room temperature treatment. This is indicated by elevatedforce values for the tomatoes stored in 13° C. storage conditionscompared with the lower force values observed with tomatoes stored inthe ambient/room conditions. Minimal distinction can be seen between thefirmness in tomatoes stored in the ozone treatment and the treatmentwith ozone and ethylene scrubbing.

Ozone concentration in the 13° C. storage treatments were effectivelyregulated and maintained within permissible levels as established byOSHA regulations. The presence of ozone in the 13° C. treatmentseffectively reduced the ethylene concentration by about ⅔, while thetreatment with additional ethylene scrubbing further reduced theethylene concentration to essentially negligible levels.

The tomatoes and bananas that were held in the ambient/room temperatureconditions on the countertop were observed to be exceptionally shriveledand soft after only 6 and 12 days, respectively. Tomatoes in thisstorage condition were also found to have mold growth after 14 daysparticularly near the stem end. It was also determined that produceexposed to the ambient/room temperature conditions lost a significantamount of moisture over the 21 day trial. Furthermore, firmnessmeasurements using a Texture Analyzer Plus (Stable Micro Systems) foundthat both the bananas and tomatoes had severely softened in the roomtemperature storage condition. Thus, storage in the ambient/roomtemperature treatment resulted in considerably diminished producequality.

Bananas and tomatoes held at 13° C. exhibited significantly bettermaintenance of quality compared with produce stored in the ambient/roomtemperature conditions. Water retention was further improved in thetreatment using ozone with additional ethylene scrubbing. Better colorretention was also observed for both the bananas and tomatoes thatreceived ozone with ethylene scrubbing. Greater levels of brown-spottingwere observed in the bananas treated with only ozone than those treatedwith ozone and ethylene scrubbing. Additionally, more extensiveshriveling and tearing of tomato flesh was observed with only ozone thanwith ozone plus ethylene scrubbing. Banana firmness was also bestpreserved in the fruit stored in the ozone with ethylene scrubbingtreatment. Thus, storage at 13° C. using ozone with additional ethylenescrubbing resulted in the highest quality produce.

1. A portable produce chamber of a sufficient size and dimension to fiton a kitchen counter top surface, comprising: An outer shell thatsubstantially defines the size and shape of the produce chamber; aninner chamber within the outer shell, the inner chamber being of asufficient size and dimension for the storage of produce; arefrigeration system separated from the inner chamber by an isolationplate; at least one ozone generation unit; at least one ethylenescrubber; and a means with the chamber for controlling temperature,ozone levels, and ethylene levels so to delay postharvest producedeterioration.
 2. The produce chamber of claim 1, further comprisingmeans to stack a portable produce chambers on another portable producechamber having a substantially similar construction.
 3. The producechamber of claim 1, wherein the produce chamber is a first producechamber having a size and dimension to be stacked on a second producechamber, the second produce chamber having substantially the same sizeand dimension as the first produce chamber.
 4. The produce chamber ofclaim 1, wherein at least one ethylene scrubber comprises potassiumpermanganate.
 5. The produce chamber of claim 1, wherein at least oneethylene scrubber comprises a titanium oxide photocatalyst.
 6. Theproduce chamber of claim 1, wherein the ozone generator is a highfrequency coronal discharge ozone generator.
 7. The produce chamber ofclaim 1, wherein the ozone generator generates ozone with ultravioletlight.
 8. The produce chamber of claim 1, wherein the refrigerationsystem maintains chamber temperature from approximately 10° C. to 20° C.9. The produce chamber of claim 1, the refrigeration system maintainschamber temperature from approximately 12° C. to 14° C.
 10. The producechamber of claim 1, wherein the ozone generator maintains the chamberozone concentration from approximately 0.05 ppm to 0.1 ppm.
 11. Theproduce chamber of claim 1, wherein the ozone generator maintains thechamber ozone concentration from approximately 0.075 ppm to 0.095 ppm.12. The produce chamber of claim 1, wherein chamber relative humidity ismaintained from approximately 80% to 100%.
 13. The produce chamber ofclaim 1, wherein chamber ethylene concentration is maintained at lessthan 0.015 ppm.
 14. A portable produce chamber comprising: a housinghaving a size and dimension to fit on a kitchen countertop, the housingcomprising an interior chamber capable of encasing produce; at least oneethylene scrubbers within the interior chamber capable of reducingchamber ethylene gas concentrations from the interior chamber to delaypostharvest produce deterioration; a refrigeration system incommunication with the interior chamber for the purpose of maintainingan chamber temperature that delays postharvest produce deterioration andfor the purpose of maintaining a relative humidity in the interiorchamber that delays postharvest produce deterioration; an isolationplate to separate components of the refrigeration system from theinterior chamber; and an ozone generator in communication with theinterior chamber for the purpose of maintaining a chamber ozoneconcentration that delays postharvest produce deterioration.
 15. Theproduce chamber of claim 13, wherein at least one ethylene scrubbercomprises potassium permanganate.
 16. The produce chamber of claim 13,wherein at least one ethylene scrubber comprises a titanium oxidephotocatalyst.
 17. The produce chamber of claim 13, wherein the ozonegenerator is a high frequency corona discharge ozone generator.
 18. Theproduce chamber of claim 13, wherein the ozone generator generates ozonewith ultraviolet light.
 19. The produce chamber of claim 13, wherein therefrigeration system maintains chamber temperature from approximately10° C. to 20° C.
 20. The produce chamber of claim 13, wherein chambertemperature is maintained from 12° C. to 14° C.
 21. The produce chamberof claim 13, wherein the ozone generator maintains the chamber ozoneconcentration from approximately 0.05 ppm to 0.1 ppm.
 22. The producechamber of claim 13, wherein the ozone generator maintains the chamberozone concentration from approximately 0.075 ppm to 0.095 ppm.
 23. Theproduce chamber of claim 13, wherein chamber relative humidity ismaintained from approximately 80% to 100%.
 24. The produce chamber ofclaim 13, wherein chamber ethylene concentration is maintained at lessthan 0.015 ppm.
 25. A method of reducing postharvest producedeterioration comprising the steps of: encasing the produce within aninterior of a portable produce chamber; separating a cooling system fromthe interior of the produce chamber with an isolation plate; cooling theinterior of the produce chamber to a temperature from about 10° C. to20° C.; introducing gaseous ozone into the interior of a chamber tomaintain a chamber ozone concentration between about 0.05 ppm and 0.15ppm; and maintaining a relative humidity within the interior of thechamber ranging from about 80% to 100% relative humidity.
 26. The methodof claim 24, further comprising the step of scrubbing ethylene from thechamber.
 27. The method of claim 24, wherein potassium permanganate isintroduced into the chamber for the purpose of ethylene scrubbing. 28.The method of claim 24, wherein a titanium oxide photocatalyst is usedto scrub ethylene from the chamber.
 29. The method of claim 24, whereinthe ozone is generated by an ozone generator in communication with thechamber.
 30. The method of claim 24, further comprising the step ofplacing the chamber on a counter top surface.
 31. The method of claim24, further comprising the step of stacking the chamber on a secondproduce chamber.
 32. The method of claim 24, wherein the chambertemperature is maintained from 12° C. to 14° C.
 33. The method of claim24, wherein the chamber ozone concentration is maintained from 0.075 ppmto 0.095 ppm.
 34. The method of claim 24, wherein the chamber relativehumidity is maintained from 80% to 100%.
 35. The method of claim 24,wherein ethylene concentration in the chamber is maintained at less than0.015 ppm.
 36. A method of reducing postharvest produce deteriorationcomprising the steps of: encasing produce within a portable, stackable,counter top, produce chamber comprising a cooling system, ozonegenerator, and ethylene scrubber; separating the cooling system from theproduce chamber using an isolation plate; maintaining the chamber at atemperature from about 10° C. to 20° C.; introducing gaseous ozone intothe chamber to maintain a chamber ozone concentration between about 0.05ppm and 0.1 ppm; maintaining a relative humidity within the chamberranging from about 70% to 100% relative humidity; scrubbing ethylenefrom the chamber with at least one potassium permanganate sachet; andmaintaining the chamber ethylene concentration at a level less thanabout 0.015 ppm.